(a) Field of the Invention
The present invention relates to a composition for an electron emitter of a Field Emission Display (hereinafter referred to as an FED) and a method for producing the electron emitter of an FED using the composition. The present invention relates more particularly to a composition for an electron emitter for forming a flat type electron emitter and a method for producing a flat type electron emitter used as a cathode in an FED.
(b) Description of the Related Art
A Field Emission Display (FED) is a type of Flat Panel Display (FPD) on which research and development is actively being pursued because it has lighter weight and less volume than conventional cathode-ray tubes (CRT). Furthermore, a Field Emission Display is advantageous because it consumes less power and is therefore appropriate for a large scale display.
As shown in FIG. 1, an FED (100) includes a front plate (20), a back plate (30), and side walls (40) and spacers (50) for enclosing and supporting the front plate (20) and back plate (30), inside of which is maintained in a vacuum condition of about 1.times.10.sup.-7 torr. The front plate (20) is generally called an anode plate. On the inside wall of the front plate (20) are formed stripe type Indium Tin Oxide (ITO) electrodes (60) that apply the required pulse voltages to each pixel. A phosphor pattern (62) is formed on the Indium Tin Oxide (ITO) electrodes (60) to display images. The back plate (30), is generally called a cathode plate. On the inside wall of the back plate Ag or ITO electrodes (70) are formed perpendicular to the ITO electrodes (60) on the front plate (20), and electron emitters (72) are coated on the electrodes (70). In this FED (100) when image signals are applied by a driver circuit (not shown) to the ITO electrodes (60) and (70), a strong electric field is formed between both electrodes. The electron emitters (72) are excited by the strong electric field, resulting in electron emission (not shown). The emitted electrons penetrate the space maintained in a vacuum condition and excite the phosphor pattern (62) to emit visible rays.
In order to fabricate this FED (100), stripe type ITO electrodes (60) are first formed by sputtering ITO on the front plate (20) and etching the sputtered ITO. Then pastes for forming the side walls (40) and the spacers (50) are printed at appropriate parallel distances and heat treated. A phosphor pattern is formed on the ITO electrodes (60) by a printing or spin coating method, and then sealing frit is coated on the edge of the front plate (20). Next, a stripe type ITO or Ag electrode (70) pattern is coated on the back plate (30) by a sputtering or screen printing method. Then pastes for forming side walls (40) and the spacers (50) are printed at appropriate parallel distances and heat treated. The electron emitter (72) pattern is formed by coating a composition of electron emitter on the electrodes (70), and then sealing frit is coated on the edge of the back plate (30). The FED (100) is fabricated by assembling the front plate (20) and the back plate (30) in parallel and heating them under an appropriate pressure to form a seal. Then the sealed FED (100) is evacuated to form a vacuum. For electron emitters (72), cone type emitters made by molybdenum deposition or by silicon sharpening, or flat type emitters using diamond or diamond like carbon (DLC), etc. are generally used.
Cone type emitters containing molybdenum (i.e., spindt type emitters) or cone type emitters containing silicon require a high vacuum environment of about 10.sup.-8 torr in the panel to minimize emitter tip damage due to remaining gas or ion impact. When this environment is not maintained, the emitter tip is likely to be damaged. Furthermore, the cone type emitters cost much more due to thin coating processes including: sputtering, exposing, etching, etc., and it is difficult to form uniform cone type emitters on a large scale substrate plate.
To fabricate the flat type emitters containing diamond or diamond like carbon, chemical vapor deposition, plasma enhanced chemical vapor deposition, laser ablation deposition, etc. are used. However, it is difficult to fabricate a large scale emitter and to provide a uniform emitter surface using these methods. Furthermore, it is economically disadvantageous due to complicated processing conditions, the high cost of necessary facilities, etc.